Four-wheel drive vehicle

ABSTRACT

A four-wheel drive vehicle has a front wheel side having a front wheel set, a rear wheel side having a rear wheel set, an engine having an output shaft extending in a transverse direction of a vehicular body, a transmission having an input shaft connected to the output shaft of the engine and an output shaft connected through a transmission mechanism to the input shaft such as to extend in a transverse direction of the vehicular body, a rotating member connected to the output shaft of the transmission, a front differential gear, a first output member connected between the rotating member and one of the wheel sets for transmitting power to one of the wheel sets through the front differential gear, a second output member coaxial with the first output member, a rear wheel propeller mechanism between the second output member and the other wheel set, and operative to convert the rotation of the second output member into rotation about an axis perpendicular to the axis of rotation of the second output member for driving the other wheel set, and a hydraulic friction clutch provided coaxially with the first and second output members to selectively connect the rotating member and the second output member.

BACKGROUND OF THE INVENTION.

This invention relates to a transversal engine four-wheel drive vehicle.

Generally, there is created rotational speed difference accompanied bydifference in a turning radius between front wheels and rear wheels inturning of a vehicle. In a part-time type four-wheel drive vehiclehaving no center differential (an operating device for dividing a powerto a front wheel drive shaft and a rear wheel drive shaft), when thevehicle is turned under a four-wheel drive condition on a paved roadwhere slippage between a road surface and drive wheels is hardlycreated, there is disadvantageously generated a return torque(rotational difference of the drive shafts) between the front wheeldrive shaft and the rear wheel drive shaft. For this reason, in case ofrunning on a road of high coefficient of friction such as a paved road,four-wheel drive is switched to two-wheel drive for purposes ofpreventing tight-corner braking due to the return torque in turning ofthe vehicle.

In the conventional part-time type four-wheel drive vehicle having atransversal engine, selection between the two-wheel drive and thefour-wheel drive is carried out by engaging and releasing an engagementtype clutch such as a dog clutch between one side power transmissionmember for normally transmitting a power to either side of front wheelsor rear wheels, or a power transmission member to be driven in receiptof the power from the one side power transmission member and the otherside power transmission member for transmitting the power to the otherside.

Therefore, the conventional part-time type four-wheel drive vehicle hasthe following problems in view of selection between the two-wheel driveand the four-wheel drive.

(1) In case of a manual transmission, as the selection between thetwo-wheel drive and the four-wheel drive during running of the vehiclemust be carried out under disengagement of a clutch, it is impossible toeffect the selection under a slip condition of wheels.

(2) In a case of an automatic transmission such as planetary geartransmission and a V-belt type CVT, the selection between the two-wheeldrive and the four-wheel drive during running of the vehicle must becarried out after setting a transmission range to a neutral condition.Therefore, the selection must be usually carried out during stop of thevehicle.

(3) As operational action of the engagement type clutch is large, it isdifficult to carry out electrical or hydraulic operating control withoutmanual operation.

SUMMARY OF THE INVENTION.

Accordingly, it is an object of the present invention to provide apart-time four-wheel drive vehicle having a transversal engine which mayeasily carry out select control and permit selection between thetwo-wheel drive and the four-wheel drive to be normally effected duringstarting of the engine without setting the transmission to a neutralcondition.

According to the present invention, there is provided a four-wheel drivevehicle comprising an engine having an output shaft extending in atransverse direction of a vehicular body, a transmission having an inputshaft connected to said output shaft of said engine and an output shaftconnected through a transmission mechanism to said input shaft in such amanner as to extend in a transverse direction of said vehicular body, arotating member connected to said output shaft of said transmission, afirst output member connected to said rotating member for transmitting apower to a front wheel side or a rear wheel side, and a hydraulicfriction clutch for effecting engagement and disengagement between saidrotating member and a second output member for transmitting a power tosaid front wheel side or said rear wheel side.

BRIEF DESCRIPTION OF THE DRAWOMG

FIGS. 1 and 2 are sectional views of a fluid transmitting device,transmission and transfer of an automatic transmission to be mounted toa transversal engine in a first preferred embodiment of the presentinvention.

FIG. 3 is a sectional view of a transfer in a second preferredembodiment of the present invention.

FIG. 4 is a sectional view of a transfer in a third preferred embodimentof the present invention.

FIG. 5 is a schematic illustration of a transfer in a fourth preferredembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show an automatic transmission in section for four-wheeldrive of a front transversal engine part-time type according to a firstembodiment of the present invention.

An automatic transmission 100 comprises a fluidic torque converter 200,transmission 300, transfer 400 for four-wheel drive and hydrauliccontrol device (not shown) fixedly provided in an oil pan under thetransmission 300.

The transmission 300 comprises an under-drive transmission 300A ofthree-forward and one-reverse range including a first planetary gear U1,second planetary gear U2, two multi-plate clutches C1 and C2 to beoperated by a hydraulic servo, band brake B1, two multi-plate brakes B2and B3, one-way clutch F1 and one-way brake F2, and an auxillarytransmission 300B including a third planetary gear U3, multi-plateclutch C3 to be operated by a hydraulic servo, multi-plate brake B4 andone-way brake F3.

A transmission case 110 of the automatic transmission 100 is constitutedof plural separate members which are tightly fixed to each other.

The torque converter 200 is accommodated in a transmission case 120opened at its right portion (on a right-hand side in the drawing), andis provided with a front cover 201 to be rotated by receiving a driveforce of a crank shaft 1 as an output shaft of an engine (not shown), anannular plate-like rear cover 202 welded to an inner circumference ofthe front cover 201, a pump impeller 203, installed to an inner wall onan inner circumferential surface of the rear cover 202, a turbine runner204 arranged in opposition to the pump impeller 203, a turbine shell 205for retaining the turbine runner 204, a stator 208 supported through aone-way clutch 206 to a fixed shaft 207 connected to the transmissioncase 110 for increasing a torque capacity when an input rotational speedis low, and a direct connecting clutch (lockup clutch) 209 arrangedbetween the front cover 201 and the turbine shell 205 for allowingsimultaneous rotation of the front cover 201 and the turbine shell 205.An internal gear oil pump 150 having an external teeth gear 150a and aninternal teeth gear 150b therein is provided between a cylindricaltransmission case 130 extending at a left portion (on a left-hand sidein the drawing) of the torque converter case 120 and the torqueconverter housing 120. An oil pump body 152 having a cylindrical portion151 rightwardly projecting at an inner circumference thereof is fixed toa right portion of the transmission case 130 housing the transmission300. An extension member 210 connected to an inner circumferential endof the rear cover 202 is engaged by spline through an innercircumference of the cylindrical portion 151 with an inner circumferenceof the external teeth gear 150a. An oil pump cover 154 having arearwardly projecting cylindrical front support 153 coaxial with thecylindrical portion 151 is fixed to a left portion of the oil pump body152. Thusly, the oil pump body 152 and the oil pump cover 154 form apartition wall 155 between the torque converter case 120 and thetransmission case 130. There are defined an under-drive mechanismchamber 130A housing the under-drive transmission 300A in an upper halfspace of the transmission case 130 and an auxiliary transmissionmechanism chamber 130B housing the auxiliary transmission 300B in alower half space thereof. At a left portion of the under-drive mechanismchamber 130A, there is provided a fixing member 157 made of aluminiumalloy which member having a rightwardly projecting cylindrical centersupport 156 and supporting an output gear 13, thus defining an outputgear housing 141 of the transmission between the fixing member 157 and arear cover 140 bolted from the left of the transmission case 130. Therear cover 140 is formed with a rightwardly projected cylindrical rearsupport coaxial with the front support 153.

At a right central portion of the cylindrical auxiliary transmissionmechanism chamber 130B provided in parallel relation with thecylindrical under-drive mechanism chamber 130A, a hole-like frontsupport 158 is mounted to the torque converter case 120. At a leftportion of the auxiliary transmission mechanism chamber 130B, a fixingmember 159 having a rightwardly projecting cylindrical inner member 159Ais fixed to the transmission case 130 by a bolt.

The fixed shaft 207 of the one-way clutch 206 for supporting the stator208 of the torque converter 200 is fitted inside of the front support153, and an input shaft 11 of the transmission 300 as an output shaft ofthe torque converter 200 is rotatably supported inside of the fixedshaft 207. The input shaft 11 is formed with a large diametrical leftend portion 11A leftwardly projecting from the front support 153, andthe left end portion 11A is formed with a leftward hole 11B at a centerthereof. A first intermediate transmitting shaft 12 arranged in a serialmanner with respect to the input shaft 11 is rotatably mounted to a leftportion of the input shaft 11. The first intermediate transmitting shaft12 is in sliding contact with the hole 10B at a right end portionthereof, and is engaged by spline with an inner hole 13B of a centralcylindrical portion 13A of the output gear 13 at a left end thereof. Thecylindrical portion 13A of the output gear 13 is supported by ballbearings 101 and 102 for allowing smooth rotation of the output gear 13which bearings are provided between the center support 156 and the rearsupport 142 of the fixing member 157 and the cylindrical portion 13A ofthe output gear 13. A sun gear shaft 14 is rotatably engaged through abearing with an outside of a right end of the first intermediatetransmitting shaft 12.

An input gear 15 of the auxiliary transmission 300B to be meshed withthe output gear 13 is supported through a roller bearing 103 to theinner member 159A at a central cylindrical portion 15A thereof. A secondintermediate transmitting shaft 16 centrally passing through theauxiliary transmission mechanism chamber 130B is engaged by spline at aleft end portion thereof with the inner hole 15B. The secondintermediate transmitting shaft 16 is formed with a flange-likeprojection 16A at an intermediate portion thereof, and is rotatablysupported through a roller bearing 104 to the hole-like front support158 at a right end portion thereof. There is formed between the rollerbearing 104 and the flange-like projection 16A on the secondintermediate transmitting shaft 16 an output gear 17A of a double-shaftautomatic transmission (a multi-range transmission comprising theunder-drive transmission 300A and the auxiliary transmission 300B)through a pair of tapered roller bearings 106 installed under adjustedprepressure with a spring member 105 interposed and a nut 16B fastenedat one end, and an output shaft 17 of the transmission 300 is supported.An output gear 17A of the output shaft 17 is meshed with a drive gearwheel 501 of the transfer 400.

A cylindrical sun gear shaft 18 is rotatably supported through a bushingbetween the flange-like projection 16A on the second intermediatetransmitting shaft 16 and the inner member 159A. A cylindrical outermember 19 is rotatably supported through a bushing on the outside of theinner member 159A. An outside of a left end of the sun gear shft 18 isengaged by spline with an inside of a right end of the outer member 19.

In the under-drive mechanism chamber 130A, at the right side thereof, afirst hydraulic servo drum 20 opened at its left portion is rotatablyengaged with the front support 153, and an annular piston 21 is fittedbetween inner and outer circumferential walls thereof to form ahydraulic servo C-2 of the clutch C2. A return spring 22 is mounted tothe inner wall side of the servo drum, while the clutch C2 is mounted tothe inside of the outer wall thereof. On the left side of the firsthydraulic servo drum 20, a second hydraulic servo drum 24 opened at itsleft portion and having an annular projection 23 at its right portion isfixed to the left end portion 11A of the input shaft 11, and an annularpiston 25 is fitted between the left end portion 11A and an outer wallof the servo drum to form a hydraulic servo C-1 of the clutch C1. Areturn spring 26 is mounted on the inner circumferential side of theservo drum, while the clutch C1 is mounted to the inside of the outerwall thereof. Further, the clutch C2 is mounted to the outercircumference of the annular projection 23, and both the first andsecond hydraulic servo drums 20 and 24 are connected through the clutchC2 with each other. On the left side of the second hydraulic servo drum24, the first planetary gear U1 is provided, and a ring gear R1 isconnected through the clutch C1 to the second hydraulic servo drum 24. Acarrier P1 is engaged by spline with a right end portion of the firstintermediate transmitting shaft 12, and a sun gear S1 is integrallyformed with the sun gear shaft 14. A connecting drum 27 so molded as tocover the first and second hydraulic servo drums 20 and 24 and the firstplanetary gear U1 in a minimum space is fixed to the outside of thefirst hydraulic servo drum 20 at a right end thereof, and is connectedto the sun gear shaft 14 at a left end thereof on the left side of thefirst planetary gear U1. Further, the band brake B1 is provided on theouter circumferential side of the servo drum.

In an excess space 27A outside of the connecting drum 27 outside of thefirst planetary gear U1, an annular third hydraulic servo drum 28 openedat its left portion is fixed, and a piston 29 is fitted to form ahydraulic servo B-2 of the brake B2. The brake B2, an outer race 31 ofthe one-way brake F2 and the multi-plate brake B3 are engaged in thisorder from the right with a spline groove 30 formed on the inside of thetransmission case 130 on the left side of the hydraulic servo B-2. Apiston 32 is fitted in an annular hole defined between the outercircumference of the center support 156 of the fixing member 157 and thetorque converter 200 to form a hydraulic servo B-3 of the mutli-platebrake B3. A return spring 33 of the hydraulic servo B-3 is supported bya flange plate 34 mounted at the right end of the center support 156.The one-way clutch F1 including the sun gear shaft 14 as an inner raceis provided inside of the multi-plate brake B2, and an outer race 35 isconnected with an inner circumference of the multi-plate brake B2. Thesecond planetary gear U2 is provided on the left side of the one-wayclutch F1. In the second planetary gear U2, a sun gear S2 is integrallyformed with the sun gear shaft 14. A carrier P2 is connected with aninner race 35A of the one-way brake F2 and with the multi-plate brakeB3. A ring gear R2 is connected with the first intermediate transmittingshaft 12.

In the third planetary gear U3 provided on the left side of the outputshaft 17, a ring gear R3 is connected through a flange plate 37 to theprojection 16A of the second intermediate transmitting shaft 16. Acarrier P3 is connected through an output drum 39 having an annularprojection 38 to be connected with the clutch C3 to a connecting sleeve40 as an input section. A sun gear S3 is formed on a sun gear shaft 18.On the left side of the third planetary gear U3, a fourth hydraulicservo drum 41 opened at its right portion is fixed to the outer member19 rotatably mounted through a bearing to the outer circumference of theinner member 159A of the fixing member 159. An annular piston 42 isfitted between an outer wall of the servo drum 41 and the outer member19 to form a hydraulic servo C-3 of the clutch C3. A return spring 43 isinstalled on the outer member 19 side, and the clutch C3 is mountedinside of the outer wall. The servo drum 41 is connected through theclutch C3 to the carrier P3. The one-way brake F3 including an innerrace of the outer member 19 is provided on the left side of the fourthhydraulic servo drum 41. On the left side of the servo drum, the brakeB4 is provided between the outer member 19 and the transmission case130. A piston 44 is fitted between the outer circumference of the innermember 159A of the fixing member 159 and the transmission case 130 toform a hydraulic servo B-4 of the brake B4. A return spring 45 is fittedin a groove formed on the outer circumferential side of the brake B4.The outer member 19 is rotated by receiving power through the carrier P3of the third planetary gear U3, the output drum 39 and the clutch C3.

The transmission 300 is designed to effect engagement or release of eachclutch and brake by hydraulic pressure selectively outputted from thehydraulic control device (not shown) to each hydraulic servo offrictional engagement devices according to running conditions of avehicle such as a vehicular speed and a throttle opening degree, therebyobtaining four forward ranges and one reverse range. There will be shownin Table 1 an example of operation and transmission range of eachclutch, brake, one-way clutch and one-way brake.

                  (TABLE 1)                                                       ______________________________________                                        CLUTCH        BRAKE        OWC                                                RANGE  C.sub.1                                                                             C.sub.2                                                                              C.sub.3                                                                           B.sub.1                                                                           B.sub.2                                                                            B.sub.3                                                                           B.sub.4                                                                           F.sub.1                                                                             F.sub.2                                                                            F.sub.3                   ______________________________________                                        P      X     X      X   X   X    X   E   f     f    f                         R      X     E      X   X   X    E   E   f     f    f                         N      X     X      X   X   X    X   E   f     f    f                         1      E     X      X   X   X    X   E   f     L    (L)                       2      E     X      X   X   E    X   E   L     f    (L)                       3      E     E      X   X   E    X   E   f     f    (L)                       4      E     E      E   X   E    X   X   f     f    f                         S                                                                             1      E     X      X   X   X    X   E   f     L    (L)                       2      E     X      X   E   E    X   E   (L)   f    (L)                       3      E     E      X   X   E    X   E   f     f    (L)                       (3)    E     E      X   X   E    X   E   f     f    (L)                       L                                                                             1      E     X      X   X   X    E   E   f     (L)  (L)                       2      E     X      X   E   E    X   E   (L)   f    (L)                       (1)    E     X      X   X   X    E   E   f     (L)  (L)                       ______________________________________                                    

In Table 1, E represents that the corresponding clutch and brake areengaged, and X represents that the corresponding clutch and brake arereleased. L represents that the corresponding one-way clutch is engagedunder engine drive condition, but such engagement is not necessarilyneeded because of the fact that power transmission is ensured by theclutch or brake arranged in parallel to the one-way clutch (Lockcondition). (L) represents that the corresponding one-way clutch isengaged only under engine drive condition, but is not engaged underengine brake condition. Further, f represents that the correspondingone-way clutch is free.

The transfer 400 comprises a drive gear wheel 410 meshing with theoutput gear 17A of the output shaft 17 of the transmission 300 andreceiving power from the output shaft 17, a differential gear case 420fastened to the drive gear wheel 410 by a bolt 411 and having a bevelgear type front differential gear 510 of a front wheel transmissionmechanism 500 for driving front wheels and a hydraulic clutch mechanism600 for selecting front-wheel drive and four-wheel drive, whichmechanism acts to transmit and cut off power to a rear wheel side outputmember 430 for converting a rotating direction and transmitting power toa rear wheel side, and rear wheel propeller mechanism 700 connected byspline with the rear wheel side output member 430 for transmitting powerto the rear wheel side.

The differential gear case 420 comprises a left case 422 rotatablysupported through a tapered roller bearing 421 on an inner circumferenceof a rightwardly projecting sleeve-like portion 131 coaxial with thefront wheel transmitting mechanism 500 of the transmission case 130, anda right case 424 rotatably supported through a tapered roller bearing423 on an inner circumference of a transfer case 160 housing a rightportion of the differential gear case 420 fixed to the right portion ofthe transmission case 130. The differential gear case 420 is fastened bythe bolt 411 together with the drive gear wheel 410.

The front wheel transmitting mechanism 500 includes a front differentialgear 510 comprising a front differential case 513 composed of a leftdifferential case 511 integrally formed with the left differential case422 of the differential gear case 420 and a right differential case 512bolted to the left differential case 511, a differential pinion shaft514 supported to the front differential case 513, a differential pinion515 rotatably supported to the differential pinion shaft 514, adifferential left side gear 516 meshed with the differential pinion 515at the left and a differential right side gear 517 meshed with thedifferential pinion 515 at the right. A front left wheel propeller shaft501 for transmitting power to a front left wheel is connected by splinewith an inner circumference of the differential left side gear 516,while a front right wheel propeller shaft 502 for transmitting power toa front right wheel is connected by spline with an inner circumferenceof the differential right side gear 517.

The hydraulic clutch mechanism 600 comprises a multi-plate clutch C4meshed with an inner spline 601 formed at an inner position of the frontdifferential gear 510 of the right case 424 of the differential gearcase 420 and with an outer spline 602 formed at a position of the rearwheel side output member 430 corresponding to the inner position of theinner spline 601, a piston 604 air-tightly fitted in an annular hole 603defined at a position of the left case 422 on the transmission 300 sideof the multi-plate clutch C4 so as to urge the multi-plate clutch C4, ahydraulic servo C-4 provided between the annular hole 603 and the piston604 for driving the piston 604 by supplying and discharging a hydraulicoil, a clutch push plate 605 provided between the multi-plate clutch C4and the piston 604 and having a fulcrum 605a projecting to the piston604 side, and a lever type return spring 607 abutting against the piston604 at its inner position, abutting against the fulcrum 605a of theclutch push plate 605 at its intermediate outer position, and beingstopped by a snap ring 606 at its outer position. Supply/dischargecontrol of the hydraulic oil to the hydraulic servo C-4 is effected by ahydraulic control device provided at a lower portion of the transmission300. A hydraulic oil supply means for supplying the hydraulic oil fromthe hydraulic control device to the hydraulic servo C-4 is formed by anoil passage (not shown) in the transmission case 130 from the hydrauliccontrol device, an oil passage 608 in the sleeve-like portion 131 fromthe oil passage in the transmission case 130, an oil passage 609 in thesleeve-like portion 131 for communicating the oil passage 608 with anouter circumference of the sleeve-like portion 131, and an oil passage610 in the left case 422 for communicating the oil passage 609 with thehydraulic servo C-4. The multi-plate clutch C4 is engaged by supplyingthe hydraulic oil to the hydraulic servo C-4 thereby to transmit anoutput of the output shaft 17 of the transmission 300 through the drivegear wheel 410, the differential gear case 420 and the multi-plateclutch C4 to the rear wheel side output member 430. Such engagement ofthe multi-plate clutch C4 is released by discharging the hydraulic oilof the hydraulic servo C-4, and the power transmitted to the right case424 is not transmitted to the rear wheel side output member 430.

The rear wheel propeller mechanism 700 comprises a gear wheel shaft 701having a front right wheel propeller shaft 502 of the front wheeltransmitting mechanism 500 on its inner circumference and connected byspline at the left end of its outer circumference with the right end ofthe inner circumference of the rear wheel side output member 430, a gearwheel 702 engaged by spline with the outer circumference of the rightportion of the gear wheel shaft 701, and a pinion 705 meshed with thegear wheel 702 and integrally formed with a rear wheel propeller shaft704 connected by spline with the outer circumference of a rear portionof a sleeve yoke 703 for transmitting power to the rear wheel side. Thegear wheel shaft 701 is rotatably supported at its intermediate portionthrough a tapered roller bearing 706 to the inner circumference of agear wheel case 170 fixed to the right side of the transfer case 160. Apropeller shaft support case 180 is designed to rotatably support thefront right wheel propeller shaft 502 fastened through a ball bearing503 to the right side of the gear wheel case 170. The gear wheel shaft701 is rotatably supported at its right portion through a tapered rollerbearing 707 and the gear wheel 702. The tapered roller bearing 707 isprovided on the inner circumference of a cylindrical boss portion 181 ofthe support case 180 which is leftwardly projected and is coaxial withthe front right wheel propeller shaft 502. The rear wheel propellershaft 704 is rotatably supported through tapered roller bearings 708 and709 to the inner circumference of a pinion case 190 fastened to the rearportion of the gear wheel case 170. Thus, the power transmitted to therear wheel side output member 430 is transmitted through the gear wheelshaft 701, gear wheel 702, pinion 705, rear wheel propeller shaft 704and sleeve yoke 703 to a rear drive wheel side.

As is mentioned above, a friction area of the multi-plate clutch isenlarged by providing the same at the outer circumferential position ofthe differential gear, thereby increasing a clutch capacity and allowingsuitable application to a vehicle having a large cylinder capacity.Further, an axial dimension of the transfer may be shortened byproviding the multi-plate clutch at the outer circumferential positionof the differential gear. Since the hydraulic friction clutch isprovided in the differential gear case, the transfer may be made compactthereby to improve installation of the same in a vehicle (hydraulicservo) of the hydraulic friction clutch is provided on the hydrauliccontrol device side of the friction engagement member (multi-plateclutch), the oil passages for supplying/discharging the hydraulic oilmay be shortened thereby to simplify the hydraulic oil supply means.Furthermore, as the lever type return spring is used for the frictionengagement means, a large engagement torque capacity may be obtained ina small space.

FIG. 3 is a sectional view of a transfer of the automatic transmissionin a second preferred embodiment of the present invention.

The transfer 400A comprises a drive gear wheel 410A meshing with theoutput gear 17A of the output shaft 17 of the transmission 300 andreceiving power from the output shaft 17, a differential gear case 420Afastened to the drive gear wheel 410A by a bolt 411A and having a bevelgear type front differential gear 510A of a front wheel transmissionmechanism 500A for driving front wheels and a hydraulic clutch mechanism600A for selecting rear-wheel drive and four-wheel drive, whichmechanism acts to transmit and cut off power to a front wheel side, andrear wheel propeller mechanism 700A connected by spline with thedifferential gear case 420A.

The differential gear case 420A comprises a left case 422A rotatablysupported through a tapered roller bearing 421A on an innercircumference of a rightwardly projecting sleeve-like portion 131Acoaxial with the front wheel transmitting mechanism 500A of thetransmission case 130, and a right case 424A rotatably supported througha tapered roller bearing 423A on an inner circumference of a transfercase 160A housing a right portion of the differential gear case 420Afixed to the right portion of the transmission case 130. Thedifferential gear case 420A is fastened by the bolt 411A together withthe drive gear wheel 410A.

The front wheel transmitting mechanism 500A includes a frontdifferential gear 510A comprising a front differential case 513Acomposed of a left differential case 511A rotatably arranged in thedifferential gear case 420A and a right differential case 512A bolted tothe left differential case 511A as a front wheel side output memberreceiving a power from the differential case 420A through the hydraulicclutch mechanism 600A, a differential pinion shaft 514A supported to thefront differential case 513A, a differential pinion 515A rotatablysupported to the differential pinion shaft 514A, a differential leftside gear 516A meshed with the differential pinion 515A at the left anda differential right side gear 517A meshed with the differential pinion515A at the right. A front left wheel propeller shaft 501A fortransmitting power to a front left wheel is connected by spline with aninner circumference of the differential left side gear 516A, while afront right wheel propeller shaft 502A for transmitting power to a frontright wheel is connected by spline with an inner circumference of thedifferential right side gear 517A.

The hydraulic clutch mechanism 600A comprises a multi-plate clutch C4Ameshed with an inner spline 601A formed at an inner position of thefront differential gear 510A of the right case 424A of the differentialgear case 420A and with an outer spline 602A formed at a position of therear wheel side output member 430A corresponding to the inner positionof the inner spline 601A formed on an outer circumference of the rightdifferential case 512A, a piston 604A air-tightly fitted in an annularhole 603A defined at a position of the left case 422A on thetransmission 300 side of the multi-plate clutch C4A so as to urge themulti-plate clutch C4A, a hydraulic servo C-4A provided between theannular hole 603A and the piston 604A for driving the piston 604A bysupplying and discharging a hydraulic oil, a clutch push plate 605Aprovided between the multi-plate clutch C4A and the piston 604A andhaving a fulcrum 605aA projecting to the piston 604A side, and a levertype return spring 607A abutting against the piston 604A at its innerposition, abutting against the fulcrum 605aA of the clutch push plate605A at its intermediate outer position, and being stopped by a snapring 606A at its outer position. Supply/discharge control of thehydraulic oil to the hydraulic servo C-4A is effected by a hydrauliccontrol device provided at a lower portion of the transmission 300. Ahydraulic oil supply means for supplying the hydraulic oil from thehydraulic control device to the hydraulic servo C-4A is formed by an oilpassage (not shown) in the transmission case 130 from the hydrauliccontrol device, an oil passage 608A in the sleeve-like portion 131A fromthe oil passage in the transmission case 130, an oil passage 609A in thesleeve-like portion 131A for communicating the oil passage 608A with anouter circumference of the sleeve-like portion 131A, and an oil passage610A in the left case 422A for communicating the oil passage 609A withthe hydraulic servo C-4A. The multi-plate clutch C4A is engaged bysupplying the hydraulic oil to the hydraulic servo C-4A thereby totransmit an output of the output shaft 17 of the transmission 300through the drive gear wheel 410A, the differential gear case 420A andthe multi-plate clutch C4A to the right differential case 512A of thefront differential case 513A. Such engagement of the multi-plate clutchC4A is released by discharging the hydraulic oil of the hydraulic servoC-4A, and the power transmitted to the right case 424A is nottransmitted to the rear wheel side output member 430A.

The rear wheel propeller mechanism 700A comprises a gear wheel shaft701A as a rear wheel side output member having a front right wheelpropeller shaft 502A of the front wheel transmitting mechanism 500A onits inner circumference and connected by spline at the left end of itsouter circumference with the right end of the inner circumference of thedifferential gear case 420A, a gear wheel 702A engaged by spline withthe outer circumference of the right portion of the gear wheel shaft701A, and a pinion 705A meshed with the gear wheel 702A and integrallyformed with a rear wheel propeller shaft 704A connected by spline withthe outer circumference of a rear portion of a sleeve yoke 703A fortransmitting power to the rear wheel side. The gear wheel shaft 701A isrotatably supported at its intermediate portion through a tapered rollerbearing 706A to the inner circumference of a gear wheel case 170A fixedto the right side of the transfer case 160A. A propeller shaft supportcase 180A is designed to rotatably support the front right wheelpropeller shaft 502A fastened through a ball bearing 503A to the rightside of the gear wheel case 170A. The gear wheel shaft 701A is rotatablysupported at its right portion through a tapered roller bearing 707A andthe gear wheel 702A. The tapered roller bearing 707A is provided on theinner circumference of a cylindrical boss portion 181A of the supportcase 180A which is leftwardly projected and is coaxial with the frontright wheel propeller shaft 502A. The rear wheel propeller shaft 704A isrotatably supported through tapered roller bearings 708A and 709A to theinner circumference of a pinion case 190A fastened to the rear portionof the gear wheel case 170A. Thus, the power normally transmitted to thedifferential gear case 420A is transmitted through the gear wheel shaft701A, gear wheel 702A, pinion 705A, rear wheel propeller shaft 704A andsleeve yoke 703A to a rear drive wheel side.

FIG. 4 is a sectional view of a transfer of the automatic transmissionin a third preferred embodiment of the present invention.

The transfer 400B comprises a drive gear wheel 410B meshing with theoutput gear 17A of the output shaft 17 of the transmission 300 andreceiving power from the output shaft 17, a differential gear case 420Bfastened to the drive gear wheel 410B by a bolt 411B and having a bevelgear type front differential gear 510B of a front wheel transmissionmechanism 500B for driving front wheels and a hydraulic clutch mechanism600B for selecting rear-wheel drive and four-wheel drive, whichmechanism acts to transmit and cut off power to a front wheel side, andrear wheel propeller mechanism 700B connected by spline with thedifferential gear case 420B.

The differential gear case 420B comprises a left case 422B rotatablysupported through a tapered roller bearing 421B on an innercircumference of a rightwardly projecting sleeve-like portion 131Bcoaxial with the front wheel transmitting mechanism 500B of thetransmission case 130, and a right case 424B rotatably supported througha tapered roller bearing 423B on an inner circumference of a transfercase 160B housing a right portion of the differential gear case 420Bfixed to the right portion of the transmission case 130. Thedifferential gear case 420B is fastened by the bolt 411B together withthe drive gear wheel 410B.

The front wheel transmitting mechanism 500B includes a frontdifferential gear 510B comprising a front differential case 513Bcomposed of a left differential case 511B as a front wheel side outputmember receiving a power from the differential gear case 420B throughthe hydraulic clutch mechanism 600B, rotatably arranged in thedifferential gear case 420B and a right differential case 512B bolted tothe left differential case 511B, a differential pinion shaft 514Bsupported to the front differential case 513B, a differential pinion515B rotatably supported to the differential pinion shaft 514B, adifferential left side gear 516B meshed with the differential pinion515B at the left and a differential right side gear 517B meshed with thedifferential pinion 515B at the right. A front left wheel propellershaft 501B for transmitting power to a front left wheel is connected byspline with an inner circumference of the differential left side gear516B, while a front right wheel propeller shaft 502B for transmittingpower to a front right wheel is connected by spline with an innercircumference of the differential right side gear 517B.

The hydraulic clutch mechanism 600B comprises a multi-plate clutch C4Bmeshed with an inner spline 601B formed on an inner circumference of aside position, that is, on the transmission 300 side, of the frontdifferential gear 510B of the right case 424B of the differential gearcase 420B and with an outer spline 602B formed at a position of the rearwheel side output member 430B corresponding to the inner position of theinner spline 601B, a piston 604B air-tightly fitted in an annular hole603B defined at a position of the left case 422B on the transmission 300side of the multi-plate clutch C4B so as to urge the multi-plate clutchC4B, a hydraulic servo C-4B provided between the annular hole 603B andthe piston 604B for driving the piston 604B by supplying and discharginga hydraulic oil, a clutch push plate 605B provided between themulti-plate clutch C4B and the piston 604B and having a fulcrum 605aBprojecting to the piston 604B side, and a lever type return spring 607Babutting against the piston 604B at its inner position, abutting againstthe fulcrum 605aB of the clutch push plate 605B at its intermediateouter position, and being stopped by an outer circumferential groove606B formed on an inner circumference of a connected portion between theleft case 422B and the right case 424B. Supply/discharge control of thehydraulic oil to the hydraulic servo C-4B is effected by a hydrauliccontrol device provided at a lower portion of the transmission 300. Ahydraulic oil supply means for supplying the hydraulic oil from thehydraulic control device to the hydraulic servo C-4B is formed by an oilpassage (not shown) in the transmission case 130 from the hydrauliccontrol device, an oil passage 608B in the sleeve-like portion 131B fromthe oil passage in the transmission case 130, an oil passage 609B in thesleeve-like portion 131B for communicating the oil passage 608B with anouter circumference of the sleeve-like portion 131B, and an oil passage610B in the left case 422B for communicating the oil passage 609B withthe hydraulic servo C-4B. The multi-plate clutch C4B is engaged bysupplying the hydraulic oil to the hydraulic servo C-4B thereby totransmit an output of the output shaft 17 of the transmission 300through the drive gear wheel 410B, the differential gear case 420B andthe multi-plate clutch C4B to the rear wheel side output member 430B.Such engagement of the multi-plate clutch C4B is released by dischargingthe hydraulic oil of the hydraulic servo C-4B, and the power transmittedto the right case 424B is not transmitted to the left differential case511B of the front differential case 513B.

The rear wheel propeller mechanism 700B comprises a gear wheel shaft701B as a rear wheel side output member having a front right wheelpropeller shaft 502B of the front wheel transmitting mechanism 500B onits inner circumference and connected by spline at the left end of itsouter circumference with the right end of the inner circumference of thedifferential gear case 420B, a gear wheel 702B engaged by spline withthe outer circumference of the right portion of the gear wheel shaft701B, and a pinion 705B meshed with the gear wheel 702B and integrallyformed with a rear wheel propeller shaft 704B connected by spline withthe outer circumference of a rear portion of a sleeve yoke 703B fortransmitting power to the rear wheel side. The gear wheel shaft 701B isrotatably supported at its intermediate portion through a tapered rollerbearing 706B to the inner circumference of a gear wheel case 170B fixedto the right side of the transfer case 160B. A propeller shaft supportcase 180B is designed to rotatably support the front right wheelpropeller shaft 502B fastened through a ball bearing 503B to the rightside of the gear wheel case 170B. The gear wheel shaft 701B is rotatablysupported at its right portion through a tapered roller bearing 707B andthe gear wheel 702B. The tapered roller bearing 707B is provided on theinner circumference of a cylindrical boss portion 181B of the supportcase 180B which is leftwardly projected and is coaxial with the frontright wheel propeller shaft 502B. The rear wheel propeller shaft 704B isrotatably supported through tapered roller bearings 708B and 709B to theinner circumference of a pinion case 190B fastened to the rear portionof the gear wheel case 170B. Thus, the power normally transmitted to thedifferential gear case 420B is transmitted through the gear wheel shaft701B, gear wheel 702B, pinion 705B, rear wheel propeller shaft 704B andsleeve yoke 703B to a rear drive wheel side.

According to the above-mentioned embodiments, as the multi-plate clutchis provided on a side position of the differential gear, a distanceamong the output shaft of the transmission, the output shaft of theengine and the output shaft of the differential gear (the front leftwheel propeller shaft 501B and the front right wheel propeller shaft502B in the preferred embodiment) may be reduced thereby to make thetransfer compact and improve installability to the vehicle.

FIG. 5 is a schematic illustration of a transfer in a fourth preferredembodiment of the present invention.

The transfer 400C comprises a drive gear wheel 410C meshing with theoutput gear 17A of the output shaft 17 of the transmission 300 andreceiving power from the output shaft 17, a differential gear case 420Cconnected to the drive gear wheel 410C by a bolt 411C and having a bevelgear type front differential gear 510C of a front wheel transmissionmechanism 500C for driving front wheels and a hydraulic clutch mechanism600C for selecting two-wheel drive and four-wheel drive, which mechanismacts to transmit and cut off power to a rear wheel side output member430C for transmitting power to a rear wheel side, and rear wheelpropeller mechanism 700C connected with the rear wheel side outputmember 430C for transmitting power to the rear wheel side.

The front wheel transmitting mechanism 500C includes a frontdifferential gear 510C comprising a front differential case 513Ccomposed of a left differential case 511C connected to the differentialgear case 420C and a right differential case 512C bolted to the leftdifferential case 511C, a differential pinion shaft 514C supported tothe front differential case 513C, a differential pinion 515C rotatablysupported to the differential pinion shaft 514C, a differential leftside gear 516C meshed with the differential pinion 515C at the left anda differential right side gear 517C meshed with the differential pinion515C at the right. A front left wheel propeller shaft 501C fortransmitting power to a front left wheel is connected with an innercircumference of the differential left side gear 516C, while a frontright wheel propeller shaft 502C for transmitting power to a front rightwheel is connected with an inner circumference of the differential rightside gear 517C.

The hydraulic clutch mechanism 600C comprises a multi-plate clutch C4Cmeshed with a side position, that is, the transmission 3003 side of thefront differential gear 510C of the differential gear case 420C and withan outer circumference of the rear wheel side output member 430C on thetransmission side from the front differential gear 510C, and a pushmeans 620C provided in the differential gear case 420C on thetransmission 300 side of the multi-plate clutch C4C for engaging anddisengaging the multi-plate clutch C4C. An output from the output shaft17 of the transmission 300 is transmitted through the drive gear wheel410C, the differential gear case 420C and the multi-plate clutch C4C tothe rear wheel side output member 430C by driving the push means 620Cand thereby engaging the multi-plate clutch C4C, and a power transmittedto the differential gear case 420C is not transmitted to the rear wheelside output member 430C by disengaging the multi-plate clutch C4C.

The rear wheel propeller mechanism 700C comprises a gear wheel shaft701C having a front right wheel propeller shaft 502C of the front wheeltransmitting mechanism 500C on its inner circumference and connected tothe rear wheel side output member 430C, a gear wheel 702C provided atthe right end of the gear wheel shaft 701C, and a pinion 705C meshedwith the gear wheel 702C and connected to a rear wheel propeller shaft704C for transmitting a power to the rear wheel side. The powertransmitted to the rear wheel side output member 430C is transmittedthrough the gear wheel shaft 701C, the gear wheel 702C, the pinion 705Cand the rear wheel propeller shaft 704C to a rear drive wheel side.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 267784/1984 (filed Dec. 19th, 1984) which isincorporated herein by reference.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

What is claimed is:
 1. A four-wheel drive vehicle comprising:a frontwheel side having a front wheel set, a rear wheel side having a rearwheel set, an engine having an output shaft extending in a transversedirection of a vehicular body, a transmission having an input shaftconnected to the output shaft of the engine and an output shaftconnected through a transmission mechanism to the input shaft such as toextend in a transverse direction of the vehicular body, a rotatingmember connected to the output shaft of the transmission, said rotatingmember being a front differential gear case incorporating a frontdifferential gear for one of said wheel sets, a first output memberconnected between the rotating member and one of the wheel sets fortransmitting power to one of the wheel sets through said frontdifferential gear, a second output member coaxial with the first outputmember, a rear wheel propeller mechanism between the second outputmember and the other wheel set, and operative to convert the rotation ofthe second output member into rotation about an axis perpendicular tothe axis of rotation of the second output member for driving the otherwheel set, and a hydraulic friction clutch provided coaxially with thefirst and second output members to selectively connect the rotatingmember and the second output member, said hydraulic friction clutchbeing arranged in an inner circumferential position of the frontdifferential gear case.
 2. The four-wheel drive vehicle as defined inclaim 1, whereinsaid hydraulic friction clutch comprises: a plurality ofclutch plates splined on the inner periphery of the front differentialgear case and an outer periphery of the second output member, a pistonslidably fitted in an annular hole of the front differential gear case,a hydraulic chamber provided in said annular hole of the frontdifferential gear case, and a return spring provided between the pistonand the front differential gear case to bias the piston toward thechamber.
 3. A four-wheel drive vehicle comprising a front wheel sidehaving a front wheel set and a rear wheel side having a rear wheel set,an engine having an output shaft extending in a transverse direction ofa vehicular body, a transmission having an input shaft connected to saidoutput shaft of said engine and an output shaft connected through atransmission mechanism to said input shaft such as to extend in atransverse direction of said vehicular body, a rotating member connectedto said output shaft of said transmission, a first output memberconnected to said rotating member for transmitting a power to one ofsaid wheel sides, said rotating member being a differential gear caseincorporating a differential gear for one of said wheel sets, and ahydraulic friction clutch for effecting engagement and disenegagementbetween said rotating member and a second output member for transmittinga power to one of said wheel sides; said hydraulic friction clutch beingarranged in an inner circumferential position of said differential gearcase.